In random stuffer box ribbon catridges the ribbon is forced by a stuffer or feed mechanism into a storage chamber where it forms random loops. The ribbon is pulled from the feed chamber on the opposite side and fed back to the stuffing mechanism to form a closed loop. The stuffing of the ribbon is essentially random and unpredictable.
One problem associated with this unpredictability is that some ribbon loops will tend to pack and others will be loose in the cartridge and that it is possible for loops of a ribbon adjacent the strand of ribbon being pulled from the storage chamber, to be pulled into the exit port or exit pinch point. When this occurs several things can happen. If the loop is fully pulled into a second chamber and then is allowed to feed out across the print point, nothing diastrous will occur. However, if a particular loop or loops trapped at the exit port is of sufficient volume that it cannot be pulled into a second chamber in its totality, the effect will be a jam which will ultimately result in failure of the cartridge and require its replacement or its disassembly. Disassembly may result in a long length of randomly stuffed ribbon being released and potentially allowed to fall out of the cartridge thus rendering the ribbon and cartridge useless.
The frictional coefficient between adjacent ribbon strands, when trapped in a constricted space, is sufficiently high that it is not possible to continue to feed the ribbon from the main storage chamber until such time as the trapped loop is consumed in the normal course of feeding.
The failures presented by jamming of the ribbon folds in the exit port are random in nature and therefore can occur on a relatively new ribbon and cartridge every bit as easily as a failure on a ribbon where the useful life of the ribbon has been substantially consumed.